Checkbox disabled

Hi,
The behavior is normal.
It depends on the parametring of Ticket Type, Activity Type and Milestone Type.

On each type, you can specify for each checkbox whether it's locked or not.
If locked (which is the default) the checkbox is checked/unchecked only depending on the status.
It is a way to ensure that the checkboxes are conform to the workflow...

Sorry this specificity is not detailed in the manual yet .
I will add an hint on this topic in "tips & tricks".

Regards.
Babynus